lavfi: add volume filter

Based on the volume filter in FFmpeg written by Stefano Sabatini
<stefasab@gmail.com>.

1 files changed, 53 insertions, 0 deletions

diff --git a/libavfilter/af_volume.h b/libavfilter/af_volume.h
new file mode 100644
index 0000000000..dec8767f88
--- /dev/null
+++ b/libavfilter/af_volume.h
@@ -0,0 +1,53 @@
+/*
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * audio volume filter
+ */
+
+#ifndef AVFILTER_AF_VOLUME_H
+#define AVFILTER_AF_VOLUME_H
+
+#include "libavutil/common.h"
+#include "libavutil/float_dsp.h"
+#include "libavutil/opt.h"
+#include "libavutil/samplefmt.h"
+
+enum PrecisionType {
+    PRECISION_FIXED = 0,
+    PRECISION_FLOAT,
+    PRECISION_DOUBLE,
+};
+
+typedef struct VolumeContext {
+    const AVClass *class;
+    AVFloatDSPContext fdsp;
+    enum PrecisionType precision;
+    double volume;
+    int    volume_i;
+    int    channels;
+    int    planes;
+    enum AVSampleFormat sample_fmt;
+
+    void (*scale_samples)(uint8_t *dst, const uint8_t *src, int nb_samples,
+                          int volume);
+    int samples_align;
+} VolumeContext;
+
+#endif /* AVFILTER_AF_VOLUME_H */